Eastside Region

LOW avalanche danger returns today for all elevations. Remain vigilant, and anticipate the possibility of small, isolated instabilities related to recent strong winds and warming temperatures. Areas in the northern portion of the forecast area that received more snowfall during the last storm are of most concern.

• LOW danger does not mean NO danger. Continue to identify terrain features of concern that may be good catchment areas for windblown snow and aspects/features that are prone to warming quickly. Watch for evidence of recent wind effects such as deep drifts or pillows, textured snow surfaces and quick transitions from firm old snow to softer conditions nearby. Rollerballs, pinwheels and sticky fresh snow are good signs that the snow surface is warming and becoming potentially unstable.
• The recent storm brought the most significant snowfall totals to the Mammoth zone and the northern portion of our forecast area. Areas closest to the Sierra crest seem to have been favored with more abundant snowfall. Field observers have found up to 8”-12” of new low-density snow in some locations. Active wind transport of this low density snow was noted in the northern portion of the forecast zone yesterday.
• A small, natural hard slab avalanche was found yesterday on the Mammoth Crest in the NE facing Red Cone Bowl. This likely occurred during a period of extreme SW winds while snow was falling this past week. This is the only report of avalanche activity we have received recently. See the observation HERE.
• Otherwise, there is limited evidence of slab development and instability following the recent snow and wind. Observers found most of the recent wind deposits to be shallow and inconsequential, or well bonded to the underlying snow surface. However, new snow settlement, warming temperatures and continued winds that are strong enough to move snow may contribute to the possibility of small slabs becoming unstable.
• In many areas we still have weak faceted snow within the snowpack. Sheltered N facing treed terrain continues to hold “recycled powder” snow, and firm wind board on N faces in the alpine was breaking down slightly into a more edgeable surface prior to this storm. A snowpit dug yesterday in Cocaine chute revealed reactive weak snow below the old bulletproof windboard. See the observation HERE. Keep this weak snow in mind if we do get a significant load of new snow, or continue to incrementally load these old snow layers with storm snow and/or wind.
• Variable sub-surface and surface conditions persist. Be prepared challenging travel conditions with hard, slick snow sometimes just a couple inches beneath the soft stuff. Boot and ski crampons and an ice-ax are still appropriate tools to keep close at hand, particularly if you are traveling in the alpine. Choose routes and conditions suited to your group’s ability.